/*
 * Copyright (c) "Neo4j"
 * Neo4j Sweden AB [https://neo4j.com]
 *
 * This file is part of Neo4j.
 *
 * Neo4j is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <https://www.gnu.org/licenses/>.
 */
package org.neo4j.kernel.impl.index.schema;

import java.time.Clock;
import java.util.concurrent.atomic.LongAccumulator;
import java.util.concurrent.atomic.LongAdder;
import org.neo4j.kernel.api.index.IndexUsageStats;

public final class DefaultIndexUsageTracking implements IndexUsageTracking {
    private final long trackedSince;
    private final LongAdder readCount = new LongAdder();
    private final LongAccumulator lastRead = new LongAccumulator(Long::max, 0);
    private final Clock clock;

    public DefaultIndexUsageTracking(Clock clock) {
        this.clock = clock;
        this.trackedSince = clock.millis();
    }

    @Override
    public IndexUsageStats getAndReset() {
        return new IndexUsageStats(lastRead.longValue(), readCount.sumThenReset(), trackedSince);
    }

    @Override
    public void queried() {
        readCount.increment();
        lastRead.accumulate(clock.millis());
    }
}
